The present invention generally relates to a pumping system. More specifically, the present invention relates to a system and a method for pumping fluid, particularly for peritoneal dialysis.
As is well known, peritoneal dialysis is a procedure for removing toxic substances and metabolites normally excreted by the kidneys and for aiding in the regulation of fluid and electrolyte balance. Peritoneal dialysis is accomplished by instilling peritoneal dialysis fluid through a conduit into a peritoneal cavity of an individual. The instilled peritoneal dialysis fluid contains ionic concentrations of electrolytes that are similar to those in the physiological extracellular fluid with the exception of lactate which is present as a bicarbonate precursor.
Fluid and solute transport occur across the peritoneal membrane between the plasma of the patient and the instilled dialysis fluid. These processes result in normalization of plasma electrolyte profiles. Toxic substances and metabolites present in high concentrations in the blood cross the peritoneal membrane into the dialyzing fluid. Dextrose, in varying concentrations, is used in the dialyzing fluid to produce a solution hyperosmolar to the plasma thus creating an osmotic gradient that facilitates fluid removal from the patient's plasma into the peritoneal cavity.
After a period of time (dwell time), the spent or used dialysis fluid is removed from the peritoneal cavity. Peritoneal dialysis is required for patients with acute or chronic renal failure when non-dialytic medical therapy is judged to be inadequate.
One form of peritoneal dialysis, continuous ambulatory peritoneal dialysis (CAPD) involves maintaining dialysis solution in constant contact with the peritoneal membrane throughout the entire day. To conduct CAPD, the patient manually drains spent dialysate and manually instills new dialysate performing a number of necessary manipulations during the procedure. CAPD relies on gravity to move fluid in and out of the peritoneal cavity. The peritoneal dialysis solution is changed approximately three to five times per day and typically four exchanges per day. Usually, three of these exchanges include dwell times of four to six hours while an overnight exchange may include a dwell time of eight to ten hours.
During the long, overnight dwell period, the efficiency of fluid removal may be reduced if the osmotic gradient is lost due to uptake of dextrose into the patient over time. Also, the ability of the dialysis fluid to promote clearance of uremic toxins is reduced once the concentration of the toxin in the dialysis fluid reaches the plasma concentration of the analyte. Thus, removing spent fluid and replacing it with fresh dialysis solution (the addition of a fifth peritoneal dialysis exchange) during the overnight period may be helpful to patients requiring additional fluid or toxin removal.
The present invention, therefore, provides a system and a method to satisfy a need of patients requiring a fifth peritoneal dialysis exchange (during sleep) or for patients who desire a more convenient method to perform four exchanges per day by skipping one daytime exchange. The present invention, therefore, provides a system and a method for a night exchange that aids in removing peritoneal dialysis solution into and out of the patient and allows the patient additional freedom of movement during the procedure.